EDK: Sprinkle some more |final| secret sauce.

mojo/edk/system/test/scoped_test_dir.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_EDK_SYSTEM_TEST_SCOPED_TEST_DIR_H_
 #define MOJO_EDK_SYSTEM_TEST_SCOPED_TEST_DIR_H_
 
 #include "base/files/scoped_temp_dir.h"
 #include "mojo/edk/util/scoped_file.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
 namespace system {
 namespace test {
 
 // Creates/destroyes a temporary directory for test purposes. (Unlike
 // |base::ScopedTempDir|, this automatically creates the temporary directory.)
-class ScopedTestDir {
+class ScopedTestDir final {
  public:
   ScopedTestDir();
   ~ScopedTestDir();
 
   util::ScopedFILE CreateFile();
 
  private:
   base::ScopedTempDir temp_dir_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ScopedTestDir);
 };
 
 }  // namespace test
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_TEST_SCOPED_TEST_DIR_H_